Simplify key_for_usage_flags
Simplify key_for_usage_flags

Generate "with implication" and "without implication" usage test cases
separately.

The set of generated test cases is unchanged. The order, and the description
of "with implication" test cases, changes.

Signed-off-by: Gilles Peskine <f805f64266d288fc5467baa7be6cd0ff366f477b@arm.com>

ARMmbed/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls